The goal of this research is to better understand the transcriptional mechanism involved in tissue specific expression of peptidases and proteases. One Of the most tissue specific peptidases identified to date is testis angiotensin converting enzyme. Therefore, I will use this enzyme as a tool to better understand the mechanism behind tissue specific expression. This study will focus on the tanscriptional factors responsible for the unique expression of this enzyme within the testis. A better understanding of this mechanism will not only further define the physiology/pathology of the tissue specific expression of angiotensin converting enzyme, it will also provide additional information regarding the basic scientific question "what makes one cell different from another cell?"